Possibly the the wheels need to be balanced. One day i put my balanced (weighted) front wheels on oppositie sides, and my car was turning to the left!

 

Not to question your intelligence at all, but are the tires unidirectional? Maybe one is on backwards when you rotated.

 

Thanks for the suggestion. I will take a look but I am fairly sure that Continental SportContact 2's aren't uni-directional. If they are I will have to start to wonder about the Audi Tech's working on it...

 

I experience the same effect with my low profile 19's. With the tires both being wider and more square-shouldered than stock, they have a large flat contact patch as compared to the stock setup, which is more rounded. The effect of driving on rutted asphault is that the tires tend to climb "up" the side of the ruts - whether the pull is to the right side or the left side depends on the shape of the ruts, the distance between them, and the position of the car on the road. It can easily pull either way. Maybe you were just driving more to one side of the road versus the other before and after switching the tires.